1. The Field of the Invention
The present invention relates to an apparatus and method for giving concrete surfaces a rough, three-dimensional texture. The texture created by the apparatus and method of the invention substantially enhances the appearance of exposed concrete surfaces in buildings.
2. Description of the Prior Art
Concrete surfaces of buildings are often roughened by such processes as sandblasting and bush hammering in order to give the surfaces a warmer, softer, three-dimensional appearance. Bush hammering, or striking the surface of the concrete with the serrated face of a bush hammer or with the plurality of small-diameter blunt points of a scaler exposes the aggregate yielding a slightly rougher, generally more appealing texture than sandblasting which does not expose as much of the aggregate.
Even though the bush hammer or scaler generally is a pneumatically-powered, concrete-chipping hammer that can make a fairly large number of strokes in a short time, bush hammering is a relatively slow and expensive process. The teeth of the serrated face of the bush hammer and the small-diameter points of the scaler become dull quickly thus necessitating frequent changes in order to maintain a consistent texture in the concrete surface. The change, required at least once and sometimes twice a day, not only consumes valuable time, but, because the heads are very costly, also creates a substantial equipment expense. Furthermore, because bush hammers and scalers are small, light tools generally held by the operator in one hand, they are not sufficiently durable for the demands of the concrete chipping process. As a result, they break down frequently adding to equipment expense and causing further time loss. Also, because of their light construction, bush hammers and scalers must be held in one spot for a substantial number of strokes in order to properly texture the surface. Finally, the serrated head of the bush hammer and the small-diameter points of the scaler grab the surface of the concrete thus requiring the operator to lift the head of the chipping hammer from a textured spot before fixing on a new spot. This constant lifting and fixing consumes an inordinate amount of time. The resultant high cost of bush hammering, four to five times that of sandblasting, renders bush hammering noncompetitive with sandblasting. Thus many architects and builders who otherwise prefer the texture of bush hammering have turned to sandblasting.
Therefore, there is a clear need for a method of giving concrete surfaces a texture at least as rough as that created by bush hammering that has a cost competitive with the cost of sandblasting. The method must utilize a high-speed, powerful hammering device that can give a concrete surface a uniformly rough texture in minimal time while resulting in minimal equipment breakage.